Infection in Patients with Rheumatoid Arthritis - article

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Infection in Patients with Rheumatoid Arthritis

11/01/2002

Most physicians consider patients with rheumatoid arthritis (RA) to

be at increased risk of serious infections relative to the general

population. With new, increasingly powerful medications for RA

therapy, many of which suppress the immune system, the risk of

infection has become a major topic of concern in the treatment of RA.

While some studies suggest that RA patients are particularly at risk

for joint and lung infections, there are few careful studies

assessing the rates of infection. A group of researchers from the

Mayo Clinic recently published two studies1,2 designed to address

these questions.

The investigators studied the medical records of more than 600 RA

patients and compared them to people without RA. In order to assess

RA patients over a long period of time, patients diagnosed with RA

from as far back as 1955 were included in the study. In total, the

researchers reviewed more than 7000 person-years of data.

The major finding was a 50% increase in the rate of infections in

patients with RA. All potential sites were more prone to infection

in RA patients, suggesting a general predisposition to infection.

Rates of infection in the joints, bone, and skin were most

substantially elevated. In addition, the severity of infection was

also increased in RA patients. Nearly twice as many RA patients

required a hospital stay for infection than people without RA. A

number of factors, both related and unrelated to RA, contribute to

the increased risk of infection, including age, lung disease, low

white blood cell count, diabetes and alcoholism, as well as the

severity of the RA.

Since many therapies for RA suppress the immune system, these

scientists also asked which RA medications increased risk for

infection. They found that corticosteroid use was associated with

increased infections, but that use of other medications was not.

From their results, these investigators conclude that patients with

RA demonstrate a significantly increased rate of infection relative

to people without RA. Their findings identify both RA-specific and

non-RA related risk factors for infection. With the exception of

corticosteroid use, the lack of an association between RA medications

and an increased risk of infection was reassuring. The authors

caution that their study is limited technically by an inability to

identify infections that were not evaluated by medical personnel

(i.e. they will miss " less serious " infections). In addition, given

the time frame of this study—patients were not evaluated after 1994—

the impact of new biologic therapies is unclear. Finally, the

population of Minnesota, where the study was conducted, is relatively

homogenous and may not reflect the US population as a whole.

Overall, however, by identifying this increased risk of infection and

by highlighting factors that may contribute to infection risk, these

studies provide useful information for RA patients and their

physicians in the ongoing effort to improve treatment of RA.

References:

1 Doran, M.F. et. al. " Frequency of infection in patients with

rheumatoid arthritis compared with controls. " Arthritis & Rheumatism

46:2287. 2002.

2 Doran, M.F. et. al. " Predictors of infection in rheumatoid

arthritis. " Arthritis & Rheumatism 46:2294. 2002.

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